Separable or deployable bodies such as satellites or probes are carried on space launch vehicles for deployment in space. Equally, solar panel arrays, antennas, deployment booms, support members and the like are commonly carried on spacecrafts as separable bodies for deployment in space to perform special functions.
These bodies must be securely restrained during launching while stowed, and, in the case of the spacecraft's appendages, through delivery of the satellite into its operational orbit.
The bodies are released and deployed on board the carrier or support structure by actuating one or more restraint devices via remote control. Proper release and deployment of the bodies are critical to ensure that they are fully operational for their intended function. As failed deployment is generally not correctable, devices that are relied on for release and deployment functions need to be fail-safe for one-time use.
Secure restraint of stowed bodies is important to prevent movement of the bodies relative to the support structure. Restraint mechanisms are known that are interposed, in one or multiple locations, between the stowed bodies and their supporting structures to inhibit their relative movement. Known restraint mechanisms include, for example, mating cup and cone type elements and serrated plates attached to adjacent separable bodies.
Using multiple releasable restraint devices (RRDs) for restraining a body from different points at distant locations on it, is a widely used solution. It provides a very stable holding configuration regarding the body being tied and the location of its centre of mass. On the other hand, when representing a statically indeterminate (hyperstatic) constraint among bodies, this same multiple point restraining solution is subject to cause forces to be present during release, due to either assembly-induced loading, or to thermoelastic loading between body and support structure caused by differences in construction and/or temperature.
Typically, a RRD comprises a base and a bracket, each attached to either the deployable body or the support structure. As introduced before, these base and bracket have mating cup-cone surfaces which interlock with one another in the stowed condition to substantially prevent lateral movement of the bodies relative to each other. Restraining mechanisms apply, at installation, a compressive pre-load to the cup-cone arrangement, often through the brackets. For the release, a remotely activated release device releases the said preload, allowing for the free separation of cup and cone surfaces and, thus, of the mechanical link between deployable body and support structure.
Various types of release devices/mechanisms (RMs) for releasing restrained bodies from support structures are known. Known release devices include explosive and non-explosive actuating (NEA) mechanisms. The explosive actuated mechanisms pyrotechnically sever a pin, cable or bolt to release the stowed body.
Typically, during the release, due to the sudden relief of the strain energy coming from the applied preload, and/or to the pyrotechnical nature of the releasing device, and/or to the detention of ejected parts, a high level of shock is expected to be generated. This high shock causes undesirable effects; in particular, it can cause damage to sensitive elements of the payload inside the deployable body.
Several enhancements on pyrotechnical release devices have been made along the years by implementing in their constructions diverse techniques and means for shock reduction. Nevertheless, these techniques and means have not succeeded, in a universal way, to contain the shock emission level for these pyrotechnical devices comfortably below the requirements requested by the applications.
Conductive thermal isolation between the restrained body and the support structure, across the restraint system are, in a majority of cases highly desirable, because it allows independent (and, therefore, modular) thermal control treatment for both the deployable body and the support structure, with null or minimized conductive heat fluxes between them.
Low thermal conductance is, thus, typically preferred for a restraint/release device. This is typically not satisfied in the desired extent by the existing restraint/release devices, which appear penalised by an often used massive metallic construction (commonly in response to the important loading capability required).
Regarding accommodation and separable-body to support-structure integration and verification aspects, a restraint/release device having the following functionalities will also appear advantageous:                Compactness        Easiness of separable body integration onto support structure        The said pre-load sensing and tuning without the need of demounting the restraint and release system from the support structure        The also said cancellation/minimisation of integration induced loads.        
Known devices for restraining and releasing of deployable bodies on space vehicles are inadequate when judged in front of all the previously identified preferred characteristics. The known devices do not incorporate the said desirable features in its whole; they do not even comprise a significantly wide extent of them. Known devices commonly incorporate few of the said desirable features, being the others separately provided either by dedicated local solutions on the deployable body or/and of the support structure at their respective attachment locations to the HRS, or simply ignored.
Thus, there is a need for a device for restraint and release of deployable bodies such as satellites or probes from space launch vehicles support structures, or such as solar arrays, antennas booms and support members from spacecrafts support structures, that complement the characteristics present in the existing devices which occasionally:
i. securely restrain the body to any of these support structures from body stowage, throughout launch and/or cruise phases as appropriate;
ii. provide reliable release, being able to separate under loads;
iii. provide substantially permanent preload monitoring, available and accessible at anytime;
iv. exhibit robust strength and stiffness values in all three translational directions;
v. have reduced size and weight, with any new, new combination, or the whole of the following ones; so that additionally, the device, in an integrated construction:
vi. substantially cancels the rotational stiffness;
vii. is able to substantially cancel integration induced loading, by providing adjustment capability among interfaces, in order to compensate for dimensional imperfections;
viii. eases the integration of the deployable body onto the support structure, by staying compatible with simple and natural procedures, and prioritising the use of standard tools;
ix. allows applying/modifying the pre-load in substantially pure-tension conditions via a built-in tightening device;
x. comprises the said built-in pure-tension tightening device, which further allows pre-load corrections with the HRS assembled onto the separable body, the support structure, or both of them;
xi. releases with low shock; and
xii. features low thermal conductance (conductive heat fluxes between the restrained body and the support structure, across the restraint system are minimized);
It can be obtained from study that new constructions of HRS systems satisfying these needs, even entirely, are feasible. The concepts and principles sustaining these new constructions represent the basis of the invention that is described next.